1. Field of the Invention
This invention relates to a method and apparatus for testing in-process materials and in particular relates to real-time testing for the concentration of a number of components, such as menthol, water, nicotine, sugars, and the like in a tobacco product.
2. Discussion of Related Art
In the production of tobacco products such as menthol cigarettes, the concentration of components such as moisture, nicotine, sugars, menthol, and the like is very important and must be monitored. Chemical processing and quality control has usually been accomplished by collecting samples from the factory floor and taking them to a laboratory at a remote site for analysis. The results usually arrive too late for any significant quality control to be effected. The more typical situation, in fact, is that the product is in the distribution pipeline before results arrive form the laboratory. This reduces any effort at quality assurance to an audit and lengthens the time necessary to perform process control studies.
Near infrared reflectance (NIR) spectroscopy has been used extensively in the agricultural industry for the past twenty years for the measurement of compounds such as sugars, and water. Filter and full spectrum analyses have been used extensively in the cigarette industry for off-line applications. Also, the cigarette industry has used this technique for on-line inspection of tobacco for the presence of moisture, although this is not a "full spectrum" analysis. Full spectrum analyses have not been used for active real-time applications in tobacco processing.